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Discussion Starter #1
what i was thinking about doing now is when i get the 3 12" is to face the box forward and seal the cabin from the trunk so as far as the subs are concerned the trunk doesn't exist. hopefully this will improve both spl and sq since the cabin area will be smaller and the bass doesn't have to bounce around in the trunk(if i just turned the box to the back) nor have the cancellation issues of facing it to the front since the only reason facing the subs to the back it louder in a "trunk" vehicle because of cancellation and help sq since the bass should appear more up front since the subs would be closer and there would be less rattling. what i was thinking of is to just seal the rear deck and run the port through a slot in the rear deck and seal up the various holes in the rear firewall and make a baffle sepperating that would seperate the enclosure from the rest of the trunk. the only problem is that i can see how to make said baffle, and to run the port through the rear deck and have it airtight but still removable. i could use snake ports to port it through the rear deck but i'm still not sure on how to make the airtight baffle
 

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I miss good ol' OT
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If I remember correctly, sealing the cabin off completely is not a good thing. Even though your car seems air tight, it can't be completley sealed as air does need to escape somewhere.

I'm not completely certain of this, but most cars have a duct of some sort that runs from the back seat into the trunk.....don't seal that up.
 

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mmmmmm SQ
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if you seal the trunk from the rest of the cabin, with subs in the trunk, you wont get any bass. And if you seal the trunk from the outside, you will have problems closing the trunk lid due to excessive pressure. If you pull back the trim on the left side of the trunk, there is a little duct that vents into the left-rear fender well to alleviate pressure.

The only time you should seal the trunk FROM THE CABIN is when running subs in an infinite baffle format. Dont do it
 

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Red line chaser
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You do not need to seal off the interior from the trunk to get some real strong bass. Sound quality wise, if the bass sounds like its coming from the rear, 90% of the time lowering the crossover low pass frequency to the subs helps cure that. Any special reason you'd like to run 3 subs that way instead of a pair? You could put a pair in a box that could be flush with the rear pass through opening and just play forward. Just an option. I had my set-up that way for a little while and saw a 142.2 db in db drag format competition. It won't hit quite as hard as pointing them backward (mine didn't), but it did sound pretty good and I didn't need as much help from the EQs to achieve a good freq response curve.
 

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Discussion Starter #5 (Edited)
whats louder 3 12's or 2 12's if there the same subs, same box type, box volume. what i want to do is point them forward and not let any bass go behind the front face where the subs will be, of the enclosure. the bass going behind the enclosure, cancelling out the front facing waves is why its louder pointing to the back instead of foward. the advantage of pointing them foward and sealing off the enclosure from the cab is because of a increase in spl do to a decrease in airspace in the cabin because as far as the subs are concerned from the front baffle back doesn't exist since they don't have to pressure that air. it should help give the illusion of upfront bass since the subs are physically closer to you and they would rattle the trunk less. i do understand that what helps give this illusion i a low crossover point, around 60-80 because the lower the frequency the less directional the sound is, and eleminating rattles since rattles are mid-high frequency which are directional which would tell your brain there is rattling behind me and the bass is causing it therefore the bass is behind me. and you can't tell me it wouldn't look cool to fold down your rear seats and see 3 12's, logo same color as your car staring at you. i guess whenever i get to building the enclosure i'll just face it foward and see what i can do with my limited amount of resources. if i can't find out a way I can do it. i'll just pointed it back and remove most of the rear deck to help the bass vent into the cabin. and the way i would mount my amp rack would help brace the rear of the chassis some more.
and with what 12's did you hit 142 to with and that was on the audiocontrol right. that 137.8 on the AC i did last summer seems so pussy of a score for a ported supersub in a compact car but i still got more deadening to do and i should have use a steady test tone insead of that freq sweep on the bass mechanik 5.0 disc.
 

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Red line chaser
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superfro86 said:
whats louder 3 12's or 2 12's if there the same subs, same box type, box volume.
Here's the catch. 3 12's will be a lil bit louder with the same amount of amplifier power, however you have to have a much larger box to hold the 3 subs and that would limit your options a bit more as far as mounting additional equipment.

superfro86 said:
what i want to do is point them forward and not let any bass go behind the front face where the subs will be, of the enclosure. the bass going behind the enclosure, cancelling out the front facing waves is why its louder pointing to the back instead of foward. the advantage of pointing them foward and sealing off the enclosure from the cab is because of a increase in spl do to a decrease in airspace in the cabin because as far as the subs are concerned from the front baffle back doesn't exist since they don't have to pressure that air.
Cancellation is not what makes the sound stronger when the box faces backward. Cancellation is when you have the rear wave of the speaker cancelling out the front wave due to poor construction and/or air leaks, which a properly built box would not have. Inside the vehicle, you have what is known as the vehicle's "transfer function", which is the boost in certain frequency bands the vehicle adds to the sound when a sub is placed within it. That's why if you take your sub box out your car and hook it up in your house, it doesn't sound close to the way it sounded in the car. It's because of the enhancement provided by the vehicle. Different vehicles have different transfer functions. When a box points backwards, you're utilizing more of that "transfer function" from the trunk, which isn't the case when the subs point forward.
superfro86 said:
and you can't tell me it wouldn't look cool to fold down your rear seats and see 3 12's, logo same color as your car staring at you.
True it would. I had 3 10's the same way and it did look slick.
superfro86 said:
and with what 12's did you hit 142 to with and that was on the audiocontrol right. that 137.8 on the AC i did last summer seems so pussy of a score for a ported supersub in a compact car but i still got more deadening to do and i should have use a steady test tone insead of that freq sweep on the bass mechanik 5.0 disc.
At that time, I had 2 12" MTX 7000's with 2 US Amps US-200's on them. Each was bridged @ 4 ohms per sub. I also used an MTX LSB-1 to help me really raise the gain to get the 142.2 db. This was on an AudioControl meter in db drag format rules. With the box turned backwards, the same subs did 144.4 db. I always think there was more potential from what I had, but I didn't want to risk blowing anything. I did both readings using the original Bass Mekanik CD.
 

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Discussion Starter #7 (Edited)
actually my amp should power the 3 12's right in the sweet spot. idq
s that are rated at 350 watts but doesn't mind a little more, running ported off a amp that does 1000 watts in at 1 ohm so the should see around 300 each. should be louder than 2 by a nice amount. i'm also considering using 3 type r's or 2 type X but i'm concerned whether the type X's be worth the extra expense if they are only going to share a killowatt. the box for the 3 12" will only be about 1/2 a cube larger than the box i'm running my idmax in due to the external port and the fact the idq's would only need 1.25 cubes each, ported.

and how would you explain the fact that if you had your subs just pointing forward and you were to open the trunk it will get louder
 
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